In the aforesaid applications I have disclosed methods of making bearing structures wherein a bondable and resin impregnated low friction thread is wound onto a structural bearing element and the resin cured to form a low friction surface on the element. In the present application I amplify upon the treatment of the thread preparatory to winding it upon the structural bearing element. This method of treatment of the thread is not restricted to the preparation of low friction thread for use only in the manufacture of bearings, or bearings of the kind illustrated in the aforesaid applications, but is also applicable to the treatment of thread for use in the manufacture of related products as, for example, are disclosed in my co-pending applications Ser. No. 332,419, entitled LOW FRICTION SEAL, filed Feb. 14, 1973, now U.S. Pat. No. 3,841,644, and Ser. No. 321,566, entitled BUSHING AND METHOD OF MAKING SAME, filed Jan. 8, 1973.
Heretofore I have disclosed in my U.S. Pats. Re.24765 and Nos. 3,037,893; 2,885,248 and 3,094,376, BEARING STRUCTURES AND METHODS OF MAKING THE SAME, wherein low friction threads are woven with bondable threads into a cloth, and the cloth is bonded to a structural bearing element to form a low friction surface thereon. While bearings thus formed have enjoyed substantial commercial success, there are certain problems in the use of the cloth, among which is the difficulty in coating the same with the proper amount of bonding resin. The interstices between the warp and woof of the cloth as well as the interstices in the thread itself take up (or sometimes do not adequately take up) the resin during the coating of the cloth which readily leads to a variable cloth-to-resin ration that is difficult to control. In the absence of close control of the cloth-to-resin ratio, bearings made with the cloth exhibit undesirable variations in both thickness, wearability and the bond of the cloth to the structural bearing element to which the cloth is secured.
The aforementioned problems inherent in the use of the cloth, as well as certain other problems, are obviated by the method of making bearings disclosed in my aforesaid pending applications. One of the reasons for this is that I am able to accurately control the amount of resin in the low friction layer which makes up the bearing surface, or in other words the resin-to-fiber ration. This arises from the fact that instead of resin impregnating the thread in the form of a cloth, I impregnate the thread itself in the form of a strand or yarn, and I am able to accurately control much more reliably the ratio of resin-to-thread.
However, the impregnation of the thread or yarn in strand form is not free of difficulties. Following considerable experimentation I conceived the method herein disclosed which is yielding satisfactory results.